Glare Evaluation of Outdoor Lighting Systems using a Luminance Analyser

Glare Evaluation of Outdoor Lighting Systems using a Luminance Analyser

Paper in proceedings outside WoS and Scopus

This article describes the possibilities of glare evaluation of outdoor lighting systems using a luminance analyser. Determining the level of glare from luminaires intended for road lighting, or from luminaires intended for lighting outdoor work areas is a challenging task, as lighting situations in outdoor environments range at several extremes. In the first case, it is the background (or road) luminance, which in many cases is very low, in contrast to the luminaire luminance, which is high. In addition, outdoor luminaires are often relatively smaller in size and therefore occupy a relatively small spatial angle in the scene, which places great demands on the resolution of the measurement technique. These extremes can therefore very realistically adversely affect the measurement result. The EN 13201 standard for the evaluation of glare from luminaires for road lighting uses the so-called TI threshold increment, which is determined practically by calculation on an ideal road section. In a real situation, the condition is often far from ideal, as real conditions enter into the assessment. Although the above mentioned standard allows for measurements using luminance cameras, the difference between calculation and measurement may in some cases give different results. This paper will present the results of several experiments in which more than 2000 images were taken and these images were then thoroughly analysed and correlated with the theoretical assumption. The results show that the theoretical values are in order of magnitude with the measured ones, but in certain situations these measurements are different due to unexpected situations. The calculation often considers a flat scene with regularly repeating light points, illuminating an ideally flat homogeneous surface. In addition, luminaires that may distort the result, such as luminaires from adjacent lighting systems, billboards, shiny building facades, etc., are often not included in the calculation. This paper is therefore intended to highlight the potential pitfalls of realistic glare assessment using luminance analysers.

This article describes the possibilities of glare evaluation of outdoor lighting systems using a luminance analyser. Determining the level of glare from luminaires intended for road lighting, or from luminaires intended for lighting outdoor work areas is a challenging task, as lighting situations in outdoor environments range at several extremes. In the first case, it is the background (or road) luminance, which in many cases is very low, in contrast to the luminaire luminance, which is high. In addition, outdoor luminaires are often relatively smaller in size and therefore occupy a relatively small spatial angle in the scene, which places great demands on the resolution of the measurement technique. These extremes can therefore very realistically adversely affect the measurement result. The EN 13201 standard for the evaluation of glare from luminaires for road lighting uses the so-called TI threshold increment, which is determined practically by calculation on an ideal road section. In a real situation, the condition is often far from ideal, as real conditions enter into the assessment. Although the above mentioned standard allows for measurements using luminance cameras, the difference between calculation and measurement may in some cases give different results. This paper will present the results of several experiments in which more than 2000 images were taken and these images were then thoroughly analysed and correlated with the theoretical assumption. The results show that the theoretical values are in order of magnitude with the measured ones, but in certain situations these measurements are different due to unexpected situations. The calculation often considers a flat scene with regularly repeating light points, illuminating an ideally flat homogeneous surface. In addition, luminaires that may distort the result, such as luminaires from adjacent lighting systems, billboards, shiny building facades, etc., are often not included in the calculation. This paper is therefore intended to highlight the potential pitfalls of realistic glare assessment using luminance analysers.

glare, luminance analyser, luminance camera

glare, luminance analyser, luminance camera

ŠKODA, J.; MOTYČKA, M.; NOVÁK, F.; BAXANT, P.

20.09.2022

Česká společnost pro osvětlování, z.s.

17. listopadu 2172/15, 708 00 Ostrava – Poruba, Czech Republic

978-80-11-02269-3

PROCEEDINGS of the 14th European Lighting Conference LUX EUROPA 2022

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